Loss of Fas Expression and Function Is Coupled with Colon Cancer Resistance to Immune Checkpoint Inhibitor Immunotherapy

Cancer stem cell markers: Symphonic masters of chemoresistance and immune evasion

Cancer Stem Cells (CSCs) are highly tumorigenic, chemoresistant, and immune evasive. They emerge as a central driver that gives rise to the bulk of tumoral mass, modifies the tumor microenvironment (TME), and exploits it, leading to poor clinical outcomes for patients with cancer. The existence of CSCs thus accounts for the failure of conventional therapies and immune surveillance. Identifying CSCs in solid tumors remains a significant challenge in modern oncology, with the use of cell surface markers being the primary strategy for studying, isolating, and enriching these cells. In this review, we explore CSC markers, focusing on the underlying signaling pathways that drive CSC self-renewal, which simultaneously makes them intrinsically chemoresistant and immune system evaders. We comprehensively discuss the autonomous and non-autonomous functions of CSCs, with particular emphasis on their interactions with the tumor microenvironment, especially immune cells. This reciprocal network enhances CSCs malignancy while compromising the surrounding niche, ultimately defining therapeutic vulnerabilities associated with each CSC marker. The most common CSCs surface markers addressed in this review-CD44, CD133, ICAM1/CD54, and LGR5-provide insights into the interplay between chemoresistance and immune evasion, two critically important phenomena in disease eradication. This new perspective on the state-of-the-art of CSCs will undoubtedly open new avenues for therapy.

The PRC2 complex epigenetically silences GATA4 to suppress cellular senescence and promote the progression of breast cancer

BACKGROUND

The transcription factor GATA4 is pivotal in cancer development but is often silenced through mechanisms like DNA methylation and histone modifications. This silencing suppresses the transcriptional activity of GATA4, disrupting its normal functions and promoting cancer progression. However, the precise molecular mechanisms and implications of GATA4 silencing in tumorigenesis remain unclear. Here, we aim to elucidate the mechanisms underlying GATA4 silencing and explore its role in breast cancer progression and its potential as a therapeutic target.

METHODS

The GATA4-breast cancer prognosis link was explored via bioinformatics analyses, with GATA4 expression measured in breast tissues. Functional gain/loss experiments were performed to gauge GATA4's impact on breast cancer cell malignancy. GATA4-PRC2 complex interaction was analyzed using silver staining and mass spectrometry. Chromatin immunoprecipitation, coupled with high-throughput sequencing, was used to identify GATA4-regulated downstream target genes. The in vitro findings were validated in an in situ breast cancer xenograft mouse model.

RESULTS

GATA4 mutation and different breast cancer subtypes were correlated, suggesting its involvement in disease progression. GATA4 suppressed cell proliferation, invasion, and migration while inducing apoptosis and senescence in breast cancer cells. The GATA4-PRC2 complex interaction silenced GATA4 expression, which altered the regulation of FAS, a GATA4 downstream gene. In vivo experiments verified that GATA4 inhibits tumor growth, suggesting its regulatory function in tumorigenesis.

CONCLUSIONS

This comprehensive study highlights the epigenetic regulation of GATA4 and its impact on breast cancer development, highlighting the PRC2-GATA4-FAS pathway as a potential target for therapeutic interventions in breast cancers.

Hallmarks of cancer resistance

This review explores the hallmarks of cancer resistance, including drug efflux mediated by ATP-binding cassette (ABC) transporters, metabolic reprogramming characterized by the Warburg effect, and the dynamic interplay between cancer cells and mitochondria. The role of cancer stem cells (CSCs) in treatment resistance and the regulatory influence of non-coding RNAs, such as long non-coding RNAs (lncRNAs), microRNAs (miRNAs), and circular RNAs (circRNAs), are studied. The chapter emphasizes future directions, encompassing advancements in immunotherapy, strategies to counter adaptive resistance, integration of artificial intelligence for predictive modeling, and the identification of biomarkers for personalized treatment. The comprehensive exploration of these hallmarks provides a foundation for innovative therapeutic approaches, aiming to navigate the complex landscape of cancer resistance and enhance patient outcomes.

Immunotherapy Study on Non-small-Cell Lung Cancer (NSCLC) Combined with Cytotoxic T Cells and miRNA34a

Immunotherapy has emerged as a promising approach for cancer treatment, and the use of microRNAs (miRNAs) as therapeutic agents has gained significant attention. In this study, we investigated the effectiveness of immunotherapy utilizing miRNA34a and Jurkat T cells in inducing cell death in non-small-cell lung cancer cells, specifically A549 cells. Moreover, we explored the impact of Jurkat T cell activation and miRNA34a delivery using iron oxide nanorods (IONRs) on the killing of cancer cells. A549 cells were cocultured with both activated and inactivated Jurkat T cells, both before and after the delivery of miRNA34a. Surprisingly, our results revealed that even inactive Jurkat T cells were capable of inducing cell death in cancer cells. This unexpected observation suggested the presence of alternative mechanisms by which Jurkat T cells can exert cytotoxic effects on cancer cells. We stimulated Jurkat T cells using anti-CD3/CD28 and analyzed their efficacy in killing A549 compared to that of the inactive Jurkat T cells in conjunction with miRNA34a. Our findings indicated that the activation of Jurkat T cells significantly enhanced their cytotoxic potential against cancer cells compared to their inactive counterparts. The combined treatment of A549 cells with activated Jurkat T cells and miRNA34a demonstrated the highest level of cancer cell death, suggesting a synergistic effect between Jurkat T cell activation and miRNA therapy. Besides the apoptosis mechanism for the Jurkat T cells' cytotoxic effects on A549 cells, we furthermore investigated the ferroptosis pathway, which was found to have an impact on the cancer cell killing due to the presence of miRNA34a and IONRs as the delivery agent inside the cancer cells.

Pirin Inhibits FAS-Mediated Apoptosis to Support Colorectal Cancer Survival

Resistance to immunotherapy in colorectal cancer (CRC) is associated with obstruction of FAS (Apo-1 or CD95)-dependent apoptosis, a hallmark of cancer. Here it is demonstrated that the upregulation of pirin (PIR) protein in colon cancers promotes tumorigenesis. Knockout or inhibition of PIR dramatically increases FAS expression, FAS-dependent apoptosis and attenuates colorectal tumor formation in mice. Specifically, NFκB2 is a direct transcriptional activator of FAS and robustly suppressed by PIR in dual mechanisms. One is the disruption of NFκB2 complex (p52-RELB) association with FAS promoter, the other is the inhibition of NIK-mediated NFκB2 activation and nuclear translocation, leading to the inability of active NFκB2 complex toward the transcription of FAS. Furthermore, PIR interacts with FAS and recruits it in cytosol, preventing its membrane translocation and assembling. Importantly, knockdown or knockout of PIR dramatically sensitizes cells to FAS mAb- or active CD8+ T cells-triggered cell death. Taken together, a PIR-NIK-NFκB2-FAS survival pathway is established, which plays a key role in supporting CRC survival.

CD95 promotes stemness of colorectal cancer cells by lncRNA MALAT1

Colorectal cancer (CRC) is the second most fatal cancer. Many studies have shown that cancer stemness contributes to resistance to conventional chemotherapy and poor prognosis. However, the mechanisms involved in maintaining cancer stemness in CRC are still obscure and few clinical drugs were used to target cancer stemness. Previous studies had reported CD95 increases the stemness of cancer cells with long-term stimulation of exogenous agonist CD95 ligand (CD95L). However, the expression of CD95L is relative low in certain human tumor tissues. In this study, we found that CD95 was highly expressed in CRC cells, and in vitro it promoted the tumorsphere formation, chemotherapy resistance and in vivo tumor growth without stimulation of exogenous CD95L. Mechanistically, the bulk and single-cell RNA-sequencing results suggested that CD95 promotes stemness of CRC cells through upregulation of long non-coding RNAs metastasis-associated lung adenocarcinoma transcript 1 (lncRNA MALAT1). MALAT1 knockdown inhibited CD95-induced tumorsphere formation and chemotherapy resistance. In summary, our findings reveal that CD95 has the capability to modulate cancer stemness via the action of the lncRNA MALAT1. Targeting CD95 may be a promising strategy to inhibit cancer stemness in CRC.

Advances in translational research of the rare cancer type adrenocortical carcinoma

Adrenocortical carcinoma is a rare malignancy with an annual worldwide incidence of 1-2 cases per 1 million and a 5-year survival rate of <60%. Although adrenocortical carcinoma is rare, such rare cancers account for approximately one third of patients diagnosed with cancer annually. In the past decade, there have been considerable advances in understanding the molecular basis of adrenocortical carcinoma. The genetic events associated with adrenocortical carcinoma in adults are distinct from those of paediatric cases, which are often associated with germline or somatic TP53 mutations and have a better prognosis. In adult primary adrenocortical carcinoma, the main somatic genetic alterations occur in genes that encode proteins involved in the WNT-β-catenin pathway, cell cycle and p53 apoptosis pathway, chromatin remodelling and telomere maintenance pathway, cAMP-protein kinase A (PKA) pathway or DNA transcription and RNA translation pathways. Recently, integrated molecular studies of adrenocortical carcinomas, which have characterized somatic mutations and the methylome as well as gene and microRNA expression profiles, have led to a molecular classification of these tumours that can predict prognosis and have helped to identify new therapeutic targets. In this Review, we summarize these recent translational research advances in adrenocortical carcinoma, which it is hoped could lead to improved patient diagnosis, treatment and outcome.

The γδ T cells dual function and crosstalk with intestinal flora in treating colorectal cancer is a promising area of study

The occurrence of colorectal cancer (CRC) is highly prevalent and severely affects human health, with the third-greatest occurrence and the second-greatest rate of death globally. Current CRC treatments, including surgery, radiotherapy, and chemotherapy, do not significantly improve CRC patients' survival rate and quality of life, so it is essential to develop new treatment strategies. Adoptive cell therapy and other immunotherapy came into being. Currently, there has been an especially significant emphasis on γδ T cells as being the primary recipient of adoptive cell therapy. The present investigation found that γδ T cells possess the capability to trigger cytotoxicity in CRC cells, secrete cytokines, recruit immune cells for the purpose of destroying cancer cells, and inhibit the progress of CRC indirectly. Nevertheless, It is possible for γδ T cells to initiate a storm of inflammatory factors and inhibit the immune response to promote the advancement of CRC. This review demonstrates a close association between the γδ T cell initiation pathway and their close association with the intestinal flora. It has been observed that the intestinal flora performs a vital function in facilitating the stimulation and functioning of γδ T cells. The tumor-fighting effect is mainly regulated by desulphurizing Vibrio and lactic acid bacteria. In contrast, the regulation of tumor-promoting impact is closely related to Clostridia and ETBF. This review systematically combs γδ T cell dual function and their relationship to intestinal flora, which offers a conceptual framework for the γδ T cell application for CRC therapies.

IRF8 Regulates Intrinsic Ferroptosis through Repressing p53 Expression to Maintain Tumor Cell Sensitivity to Cytotoxic T Lymphocytes

Ferroptosis has emerged as a cytotoxic T lymphocyte (CTL)-induced tumor cell death pathway. The regulation of tumor cell sensitivity to ferroptosis is incompletely understood. Here, we report that interferon regulatory factor 8 (IRF8) functions as a regulator of tumor cell intrinsic ferroptosis. Genome-wide gene expression profiling identified the ferroptosis pathway as an IRF8-regulated pathway in tumor cells. IRF8.KO tumor cells acquire resistance to intrinsic ferroptosis induction and IRF8-deficient tumor cells also exhibit decreased ferroptosis in response to tumor-specific CTLs. Irf8 deletion increased p53 expression in tumor cells and knocking out p53 in IRF8.KO tumor cells restored tumor cell sensitivity to intrinsic ferroptosis induction. Furthermore, IRF8.KO tumor cells grew significantly faster than WT tumor cells in immune-competent mice. To restore IRF8 expression in tumor cells, we designed and synthesized codon usage-optimized IRF8-encoding DNA to generate IRF8-encoding plasmid NTC9385R-mIRF8. Restoring IRF8 expression via a lipid nanoparticle-encapsulated NTC9385R-mIRF8 plasmid therapy suppressed established tumor growth in vivo. In human cancer patients, nivolumab responders have a significantly higher IRF8 expression level in their tumor cells as compared to the non-responders. Our data determine that IRF8 represses p53 expression to maintain tumor cell sensitivity to intrinsic ferroptosis.

IRF8: Mechanism of Action and Health Implications

Interferon regulatory factor 8 (IRF8) is a transcription factor of the IRF protein family. IRF8 was originally identified as an essentialfactor for myeloid cell lineage commitment and differentiation. Deletion of Irf8 leads to massive accumulation of CD11b⁺Gr1⁺ immature myeloid cells (IMCs), particularly the CD11b⁺Ly6C^hi/+Ly6G⁻ polymorphonuclear myeloid-derived suppressor cell-like cells (PMN-MDSCs). Under pathological conditions such as cancer, Irf8 is silenced by its promoter DNA hypermethylation, resulting in accumulation of PMN-MDSCs and CD11b⁺ Ly6G⁺Ly6C^lo monocytic MDSCs (M-MDSCs) in mice. IRF8 is often silenced in MDSCs in human cancer patients. MDSCs are heterogeneous populations of immune suppressive cells that suppress T and NK cell activity to promote tumor immune evasion and produce growth factors to exert direct tumor-promoting activity. Emerging experimental data reveals that IRF8 is also expressed in non-hematopoietic cells. Epithelial cell-expressed IRF8 regulates apoptosis and represses Osteopontin (OPN). Human tumor cells may use the IRF8 promoter DNA methylation as a mechanism to repress IRF8 expression to advance cancer through acquiring apoptosis resistance and OPN up-regulation. Elevated OPN engages CD44 to suppress T cell activation and promote tumor cell stemness to advance cancer. IRF8 thus is a transcription factor that regulates both the immune and non-immune components in human health and diseases.

Lipid Nanoparticle Delivery of Fas Plasmid Restores Fas Expression to Suppress Melanoma Growth In Vivo

Fas ligand (FasL), expressed on the surface of activated cytotoxic T lymphocytes (CTLs), is the physiological ligand for the cell surface death receptor, Fas. The Fas-FasL engagement initiates diverse signaling pathways, including the extrinsic cell death signaling pathway, which is one of the effector mechanisms that CTLs use to kill tumor cells. Emerging clinical and experimental data indicate that Fas is essential for the efficacy of CAR-T cell immunotherapy. Furthermore, loss of Fas expression is a hallmark of human melanoma. We hypothesize that restoring Fas expression in tumor cells reverses human melanoma resistance to T cell cytotoxicity. DNA hypermethylation, at the FAS promoter, down-regulates FAS expression and confers melanoma cell resistance to FasL-induced cell death. Forced expression of Fas in tumor cells overcomes melanoma resistance to FasL-induced cell death in vitro. Lipid nanoparticle-encapsulated mouse Fas-encoding plasmid therapy eliminates Fas⁺ tumor cells and suppresses established melanoma growth in immune-competent syngeneic mice. Similarly, lipid nanoparticle-encapsulated human FAS-encoding plasmid (hCOFAS01) therapy significantly increases Fas protein levels on tumor cells of human melanoma patient-derived xenograft (PDX) and suppresses the established human melanoma PDX growth in humanized NSG mice. In human melanoma patients, FasL is expressed in activated and exhausted T cells, Fas mRNA level positively correlates with melanoma patient survival, and nivolumab immunotherapy increases FAS expression in tumor cells. Our data demonstrate that hCOFAS01 is an effective immunotherapeutic agent for human melanoma therapy with dual efficacy in increasing tumor cell FAS expression and in enhancing CTL tumor infiltration.

Orexin A Suppresses the Expression of Exosomal PD-L1 in Colon Cancer and Promotes T Cell Activity by Inhibiting JAK2/STAT3 Signaling Pathway

BACKGROUND

Colon cancer, ranked third in cancer related mortality, is the most common malignant cancer of digestive tract. Though immune checkpoint inhibitors show promising efficacy in colon cancer, a rather high unresponsive rate and recurrence rate requires further elucidation of the underlying regulatory mechanism of cancer-related immunity.

AIMS

To study the regulatory function of Orexin A in the expression of exosomal PD-L1 and T cell activity.

METHODS

Orthotopic colon cancer transplantation mice model were established to study the cancer growth and immune infiltration between Orexin A treated group and untreated group. In vitro studies using mouse CT-26 and human HCT-116 colon cancer cell model studied the effect of Orexin A on cellular and exosomal PD-L1 expression. Co-culturing Jurkat cells with exosomes delivered by cancer cells treated with Orexin A, PD-L1 knockdown and PBS studied different effects on T cell. Comparing Orexin A with WP1066, a JAK2/STAT3 inhibitor verified the mechanism of these changes.

RESULTS

The growth rate of orthotopic transplanted colon cancer was slower in Orexin A treated group, with lower PD-L1 expression and higher immune infiltration. Orexin A could inhibit cellular and exosomal PD-L1 expression. The decreased expression of PD-L1 in exosomes could promote the activity of Jurkat cells secreting higher level of IFN-γ and IL-2. Orexin A showed a similar effect like WP1066 which proved JAK2/STAT3 signaling pathway was its downstream signaling pathway.

CONCLUSIONS

Orexin A could suppress the expression of exosomal PD-L1 in colon cancer cells and promote T cells activity by inhibiting JAK2/STAT3 signaling pathway.

Identification of a Novel Immune Landscape Signature for Predicting Prognosis and Response of Colon Cancer to Immunotherapy

Purpose

To construct an immune-related gene prognostic index (IRGPI) for colon cancer and elucidate the molecular and immune characteristics as well as the benefit of immune checkpoint inhibitor (ICI) therapy in IRGPI-defined groups of colon cancer.

Experimental Design

Transcriptional and clinical data of colon cancer samples were obtained from The Cancer Genome Atlas (TCGA) (n = 521). Immune-related genes were obtained from ImmPort and InnateDB databases. 21 immune-related hub genes were identified byweighted gene co-expression network analysis (WGCNA). the Cox regression method was used to construct IRGPI and validated with Gene Expression Omnibus (GEO) dataset (n = 584). Finally, the molecular and immune profiles in the groups defined by IRGPI and the benefit of ICI treatment were analyzed.

Results

8 genes were identified to construct IRGPI. IRGPI-low group had a better overall survival (OS) than IRGPI-high group. And this was well validated in the GEO cohort. Overall results showed that those with low IRGPI scores were enriched in antitumor metabolism, and collated with high infiltration of resting memory CD4 T cells and less aggressive phenotypes, benefiting more from ICI treatment. Conversely, high IRGPI scores were associated with cell adhesion molecules (CAMs) and chemokine signaling pathways, high infiltration of macrophage M1, suppressed immunity, more aggressive colon cancer phenotypes, as well as reduced therapeutic benefit from ICI treatment.

Conclusions

IRGPI is a promising biomarker to differentiate the prognostic and molecular profile of colon cancer, as well as the therapeutic benefits of ICI treatment.

SRSF6 Regulates the Alternative Splicing of the Apoptotic Fas Gene by Targeting a Novel RNA Sequence

Simple Summary

Alternative splicing (AS) produces multiple mRNA isoforms from a gene to make a large number of proteins. Fas (Apo-1/CD95) pre-mRNA, a member of TNF receptor family that mediates apoptosis, can generate pro-apoptotic and anti-apoptotic proteins through AS. Here, we identified SRSF6 as an essential regulator protein in Fas AS. We further located a new functional target sequence of SRSF6 in Fas splicing. In addition, our large-scale RNA-seq analysis using GTEX and TCGA indicated that while SRSF6 expression was correlated with Fas expression in normal tissues, the correlation was disrupted in tumors. Our results suggest a novel regulatory mechanisms of Fas AS.

Abstract

Alternative splicing (AS) is a procedure during gene expression that allows the production of multiple mRNAs from a single gene, leading to a larger number of proteins with various functions. The alternative splicing (AS) of Fas (Apo-1/CD95) pre-mRNA can generate membrane-bound or soluble isoforms with pro-apoptotic and anti-apoptotic functions. SRSF6, a member of the Serine/Arginine-rich protein family, plays essential roles in both constitutive and alternative splicing. Here, we identified SRSF6 as an important regulatory protein in Fas AS. The cassette exon inclusion of Fas was decreased by SRSF6-targeting shRNA treatment, but increased by SRSF6 overexpression. The deletion and substitution mutagenesis of the Fas minigene demonstrated that the UGCCAA sequence in the cassette exon of the Fas gene causes the functional disruption of SRSF6, indicating that these sequences are essential for SRSF6 function in Fas splicing. In addition, biotin-labeled RNA-pulldown and immunoblotting analysis showed that SRSF6 interacted with these RNA sequences. Mutagenesis in the splice-site strength alteration demonstrated that the 5′ splice-site, but not the 3′ splice-site, was required for the SRSF6 regulation of Fas pre-mRNA. In addition, a large-scale RNA-seq analysis using GTEX and TCGA indicated that while SRSF6 expression was correlated with Fas expression in normal tissues, the correlation was disrupted in tumors. Furthermore, high SRSF6 expression was linked to the high expression of pro-apoptotic and immune activation genes. Therefore, we identified a novel RNA target with 5′ splice-site dependence of SRSF6 in Fas pre-mRNA splicing, and a correlation between SRSF6 and Fas expression.

Mapping Proteome Changes in Microsatellite Stable, Recurrent Colon Cancer Reveals a Significant Immune System Signature

BACKGROUND/AIM

Better stratification of the risk of relapse will help select the right patients for adjuvant treatment and improve targeted therapies for patients with colon cancer.

MATERIALS AND METHODS

To understand why a subset of tumors relapse, we compared the proteome of two groups of patients with colon cancer with similar stage, stratified based on the presence or absence of recurrence.

RESULTS

Using tumor biopsies from the primary operation, we identified dissimilarity between recurrent and nonrecurrent mismatch satellite stable colon cancer and found that signaling related to immune activation and inflammation was associated with relapse.

CONCLUSION

Immune modulation may have an effect on mismatch satellite stable colon cancer. At present, immune therapy is offered primarily to microsatellite instable colon cancer. Hopefully, immune therapy in mismatch satellite stable colon cancer beyond PD-1 and PD-L1 inhibitors can be implemented.

LINC00630 as a miR-409-3p sponge promotes apoptosis and glycolysis of colon carcinoma cells via regulating HK2

Long-chain non-coding RNAs (lncRNAs) belong to the family of non-coding RNAs and contain more than 200 nucleotides. They are involved in the growth, apoptosis, and glycolysis of carcinoma cells. A newly discovered lncRNA, LINC00630, has been reported in colon carcinoma. In this study, we found that the expression of LINC00630 was remarkably upregulated in colon carcinoma tissues and cell lines compared with that in adjacent tissues and the NCM-460 cell lines. Knocking out LINC00630 resulted in inhibition of proliferation and glycolysis but increase in apoptosis. In addition, we confirmed the direct interaction between LINC00630 and miR-409-3p in colon carcinoma cells using bioinformatics methods and dual luciferase reporter gene assay. Finally, we demonstrated that LINC00630 could promote cell growth and glycolysis and inhibit apoptosis by functioning as a miR-409-3p sponge, and further regulate hexokinase 2 (HK2) in colon carcinoma cells. Our results confirmed that LINC00630 regulates proliferation, glycolysis, and apoptosis mainly through targeting the miR-409-3p/HK2 axis, which may explain the progression of colon carcinoma and provide a potential target for the treatment of colon carcinoma.

Restoring FAS Expression via Lipid-Encapsulated FAS DNA Nanoparticle Delivery Is Sufficient to Suppress Colon Tumor Growth In Vivo

Simple Summary

A key feature of human colorectal tumor is loss of FAS expression. FAS is the death receptor for FASL of activated T cells. Loss of FAS expression therefore may promote tumor cell immune escape. We aimed at determining whether restoring FAS expression is sufficient to suppress colorectal tumor growth. Mouse and human FAS cDNA was synthesized and encapsulated into cationic lipid nanoparticle DOTAP-Cholesterol to formulate DOTAP-Chol-mFAS and DOTAP-Chol-hFAS, respectively. Restoring FAS expression in metastatic mouse colon-tumor cells enabled FASL-induced elimination of FAS⁺ tumor cells in vitro and suppressed colon-tumor growth and progression in tumor-bearing mice in vivo. Restoring FAS expression induced FAS receptor auto-oligomerization and tumor cell auto-apoptosis in metastatic human colon-tumor cells in vitro. DOTAP-Chol-hFAS therapy is also sufficient to suppress metastatic human colon tumor xenograft growth in athymic mice. Tumor-selective delivery of FAS DNA nanoparticle is potentially an effective therapy for human colorectal cancer.

Abstract

A hallmark of human colorectal cancer is lost expression of FAS, the death receptor for FASL of cytotoxic T lymphocytes (CTLs). However, it is unknown whether restoring FAS expression alone is sufficient to suppress csolorectal-cancer development. The FAS promoter is hypermethylated and inversely correlated with FAS mRNA level in human colorectal carcinomas. Analysis of single-cell RNA-Seq datasets revealed that FAS is highly expressed in epithelial cells and immune cells but down-regulated in colon-tumor cells in human colorectal-cancer patients. Codon usage-optimized mouse and human FAS cDNA was designed, synthesized, and encapsulated into cationic lipid to formulate nanoparticle DOTAP-Chol-mFAS and DOTAP-Chol-hFAS, respectively. Overexpression of codon usage-optimized FAS in metastatic mouse colon-tumor cells enabled FASL-induced elimination of FAS⁺ tumor cells in vitro, suppressed colon tumor growth, and increased the survival of tumor-bearing mice in vivo. Overexpression of codon-optimized FAS-induced FAS receptor auto-oligomerization and tumor cell auto-apoptosis in metastatic human colon-tumor cells. DOTAP-Chol-hFAS therapy is also sufficient to suppress metastatic human colon tumor xenograft growth in athymic mice. DOTAP-Chol-mFAS therapy exhibited no significant liver toxicity. Our data determined that tumor-selective delivery of FAS DNA nanoparticles is sufficient for suppression of human colon tumor growth in vivo.

An Apoptosis-Related Gene Prognostic Index for Colon Cancer

Purpose: To construct an apoptosis-related gene prognostic index (ARGPI) for colon cancer, and clarify the molecular and immune characteristics of the risk subgroup as defined by the prognostic index and the benefits of adjuvant chemotherapy. Integrating the prognostic index and clinicopathological risk factors to better evaluate the prognosis of patients with colon cancer. Methods: Based on the colon adenocarcinoma data in the TCGA database, 20 apoptosis-related hub genes were screened by weighted gene co-expression network analysis (WGCNA). Five genes constituting the prognosis model were determined by Cox regression and verified by the Gene Expression Omnibus (GEO) dataset. Then the molecular and immune characteristics of risk subgroups defined by the prognostic index and the benefits of adjuvant chemotherapy were analyzed. Finally, nomograms integrating ARGPI and four clinicopathological risk factors were used to evaluate the prognosis of patients with colon cancer. Results: The ARGPI was constructed based on the FAS, VWA5A, SPTBN2, PCK1, and TIMP1 genes. In the TCGA cohort, patients in the low-risk subgroup had a longer progression-free interval (PFI) than patients in the high-risk subgroup, which coincided with the results of the GEO cohort. The comprehensive results showed that the high-risk score was related to the enrichment of the cell cycle pathway, high mutation rate of TP53 and KRAS, high infiltration of T regulatory cells (Tregs), immunosuppressive state, and less chemotherapeutic benefit. However, low-risk scores are related to drug metabolism-related pathways, low TP53 and KRAS mutation rates, high infiltration of plasma cells, more resting CD4 memory cells and eosinophils, active immune function, and better chemotherapeutic benefits. Receiver operating characteristic curve of two-year progress prediction evaluation showed that the ARGPI had higher prognostic accuracy than TNM staging. Nomograms integrating ARGPI and clinicopathological risk factors can better evaluate the prognosis of patients with colon cancer. Conclusions: The ARGPI is a promising biomarker for determining risk of colon cancer progression, molecular and immune characteristics, and chemotherapeutic benefit. This is a reliable method to predict the prognosis of colon cancer patients. It also can assist doctors in formulating more effective treatment strategies.

Interaction between Microsatellite Instability (MSI) and Tumor DNA Methylation in the Pathogenesis of Colorectal Carcinoma

Simple Summary

In colorectal cancer (CRC), mutations may occur in short, repeated DNA sequences, known as microsatellite instability (MSI). Tumor DNA methylation is another molecular change now recognized as an important biomarker in CRC. In a genome-wide scale, for the first time, we explored whether DNA methylation is associated with MSI status in CRC. We analyzed 250 paired samples (tumor and corresponding normal) from 125 CRC patients (m = 72, f = 53) at different stages. We found that many genes were methylated in tumor tissue compared to normal tissue. However, almost four times more genes showed such methylation changes in the tumor if the patient who also had MSI compared to patients without MSI. Our study shows an association of MSI and DNA methylation in CRC. The study also indicates an opportunity for potential use of certain immune checkpoint inhibitors (CTLA4 and HAVCR2 inhibitors) in CRC with MSI.

Abstract

In colorectal cancer (CRC), the role of microsatellite instability (MSI) is well known. In a genome-wide scale, for the first time, we explored whether differential methylation is associated with MSI. We analyzed 250 paired samples from 125 CRC patients (m = 72, f = 53) at different stages. Of them, 101 had left-sided CRC, 30 had MSI, 34 had somatic mutation in KRAS proto-oncogene (KRAS), and 6 had B-Raf proto-oncogene (BRAF) exon 15p.V600E mutation. MSI was more frequent in right-sided tumors (54% vs. 17%, p = 0.003). Among the microsatellite stable (MSS) CRC, a paired comparison revealed 1641 differentially methylated loci (DML) covering 686 genes at FDR 0.001 with delta beta ≥ 20%. Similar analysis in MSI revealed 6209 DML covering 2316 genes. ANOVA model including interaction (Tumor*MSI) revealed 23,322 loci, where the delta beta was different among MSI and MSS patients. Our study shows an association between MSI and tumor DNA methylation in the pathogenesis of CRC. Given the interaction seen in this study, it may be worth considering the MSI status while looking for methylation markers in CRC. The study also indicates an opportunity for potential use of certain immune checkpoint inhibitors (CTLA4 and HAVCR2 inhibitors) in CRC with MSI.

Pan-drug and drug-specific mechanisms of 5-FU, irinotecan (CPT-11), oxaliplatin, and cisplatin identified by comparison of transcriptomic and cytokine responses of colorectal cancer cells

Colorectal cancer (CRC) caused over 900,000 deaths worldwide in 2020. A majority of late-stage CRC patients are treated with 5-fluorouracil (5-FU) combined with either irinotecan (CPT-11), oxaliplatin, or both. Despite their widespread use, the mechanisms of efficacy and toxicity of these drugs remain incompletely understood. While previous work has investigated cellular responses to these agents individually, we directly compare the transcriptomic and cytokine profiles of HCT116 wild-type and p53-/- colorectal cancer cells treated with these drugs and report pan-drug, drug-specific, drug class-specific, p53-independent, and p53-dependent signatures. We observed downregulation of histone genes by 5-FU (that significantly correlates with improved survival in CRC patients) and upregulation of FOS and ATF3 by oxaliplatin (which may contribute to peripheral neuropathy). BTG2 was identified as a top gene upregulated by all four drugs, suggesting its critical role in the cellular response to chemotherapy in CRC. Soluble TRAILR2 (death receptor 5; DR5) is a decoy receptor for TRAIL, an apoptosis-inducing cytokine. TRAILR2 was down-regulated by oxaliplatin and 5-FU, was not affected by CPT-11, and was increased by cisplatin. There was an increase in IL-8 by oxaliplatin and increase in ferritin by cisplatin which may contribute to cancer cell survival. Novel drug-specific mechanisms of efficacy or toxicity identified in these signatures may be targeted with combination therapies or development of new targeted therapies. Together, the findings here contribute to our understanding of the molecular bases of efficacy and toxicity of chemotherapeutic agents often used for treatment of GI cancer such as CRC.

Apoptotic Extracellular Vesicles Ameliorate Multiple Myeloma by Restoring Fas-Mediated Apoptosis

Apoptosis is critical for maintaining bodily homeostasis and produces a large number of apoptotic extracellular vesicles (apoEVs). Several types of cancer cells display reduced expression of Fas on the cell surface and are thus capable of escaping Fas ligand-induced apoptosis. However, it is unknown whether normal cell-derived apoEVs can regulate tumor growth. In this study, we show that apoEVs can induce multiple myeloma (MM) cell apoptosis and inhibit MM cell growth. Systemic infusion of mesenchymal stem cell (MSC)-derived apoEVs significantly prolongs the lifespan of MM mice. Mechanistically, apoEVs directly contact MM cells to facilitate Fas trafficking from the cytoplasm to the cell membrane by evoking Ca²⁺ influx and elevation of cytosolic Ca²⁺. Subsequently, apoEVs use their Fas ligand to activate the Fas pathway in MM cells, leading to the initiation of apoptosis. This study identifies the role of apoEVs in inducing MM apoptosis and suggests a potential for apoEVs to treat MM.

Recent Updates on Mechanisms of Resistance to 5-Fluorouracil and Reversal Strategies in Colon Cancer Treatment

5-Fluorouracil (5-FU) plus leucovorin (LV) remain as the mainstay standard adjuvant chemotherapy treatment for early stage colon cancer, and the preferred first-line option for metastatic colon cancer patients in combination with oxaliplatin in FOLFOX, or irinotecan in FOLFIRI regimens. Despite treatment success to a certain extent, the incidence of chemotherapy failure attributed to chemotherapy resistance is still reported in many patients. This resistance, which can be defined by tumor tolerance against chemotherapy, either intrinsic or acquired, is primarily driven by the dysregulation of various components in distinct pathways. In recent years, it has been established that the incidence of 5-FU resistance, akin to multidrug resistance, can be attributed to the alterations in drug transport, evasion of apoptosis, changes in the cell cycle and DNA-damage repair machinery, regulation of autophagy, epithelial-to-mesenchymal transition, cancer stem cell involvement, tumor microenvironment interactions, miRNA dysregulations, epigenetic alterations, as well as redox imbalances. Certain resistance mechanisms that are 5-FU-specific have also been ascertained to include the upregulation of thymidylate synthase, dihydropyrimidine dehydrogenase, methylenetetrahydrofolate reductase, and the downregulation of thymidine phosphorylase. Indeed, the successful modulation of these mechanisms have been the game plan of numerous studies that had employed small molecule inhibitors, plant-based small molecules, and non-coding RNA regulators to effectively reverse 5-FU resistance in colon cancer cells. It is hoped that these studies would provide fundamental knowledge to further our understanding prior developing novel drugs in the near future that would synergistically work with 5-FU to potentiate its antitumor effects and improve the patient's overall survival.

Perspectives on Immunotherapy of Metastatic Colorectal Cancer

Colorectal cancer, especially liver metastasis, is still a challenge worldwide. Traditional treatment such as surgery, chemotherapy and radiotherapy have been difficult to be further advanced. We need to develop new treatment methods to further improve the poor prognosis of these patients. The emergence of immunotherapy has brought light to mCRC patients, especially those with dMMR. Based on several large trials, some drugs (pembrolizumab, nivolumab) have been approved by US Food and Drug Administration to treat the patients diagnosed with dMMR tumors. However, immunotherapy has reached a bottleneck for other MSS tumors, with low response rate and poor PFS and OS. Therefore, more clinical trials are underway toward mCRC patients, especially those with MSS. This review is intended to summarize the existing clinical trials to illustrate the development of immunotherapy in mCRC patients, and to provide a new thinking for the direction and experimental design of immunotherapy in the future.

Tumor Microenvironment in Adrenocortical Carcinoma: Barrier to Immunotherapy Success?

Adrenocortical carcinoma is a rare malignancy with aggressive behavior, with up to 40% of patients presenting with metastases at the time of diagnosis. Both conventional chemotherapeutic regimens and novel immunotherapeutic agents, many of which are currently being tested in ongoing clinical trials, have yielded modest results so far, bringing the need for a deeper understanding of adrenal cancer behavior to the forefront. In the recent years, the tumor microenvironment has emerged as a major determinant of cancer response to immunotherapy and an increasing number of studies on other solid tumors have focused on manipulating the microenvironment in the favor of the host and discovering new potential target molecules. In the present review we aim to explore the characteristics of adrenocortical cancer's microenvironment, highlighting the mechanisms of immune evasion responsible for the modest immunotherapeutic results, and identify novel potential strategies.

Fas-Fas Ligand Interplay in the Periphery of Salivary Gland Carcinomas as a New Checkpoint Predictor for Disease Severity and Immunotherapy Response

Salivary gland carcinomas (SGCs) are extremely morphologically heterogeneous, and treatment options for this disease are limited. Immunotherapy with immune checkpoint inhibitors (ICIs) represents a revolutionary treatment approach. However, SGCs remain largely resistant to this therapy. An increasing body of evidence suggests that resistance to ICI therapy is modulated by the Fas (CD95)–Fas ligand (FasL, CD178) interplay between tumor cells and immune cells. In this study, we examined the Fas–FasL interplay between tumor cells and tumor-infiltrating immune cells (TIICs) in the center and periphery of SGCs from 62 patients. We found that the Fas-expressing tumor cells accumulated in the center of SGC tumors with increasing tumor stage. Furthermore, this accumulation occurred regardless of the presence of TIICs expressing high levels of FasL. On the contrary, a loss of Fas-expressing TIICs with increasing tumor stage was found in the tumor periphery, whereas FasL expression in tumor cells in the tumor periphery correlated with tumor stage. These data suggest that SGC cells are resistant to FasL-induced apoptosis by TIICs but could utilize FasL to eliminate these cells in high-stage tumors to provide resistance to immunotherapy.

CD95L and Anti-Tumor Immune Response: Current Understanding and New Evidence

The ability of FasL/CD95L to induce apoptosis in various Fas/CD95-expressing cells has been described in the context of hematopoiesis or thymic elimination of self-reactive T cells and resolution of an acute immune response under physiological conditions. At the same time, non-apoptotic CD95 activation is widely described in cancer and shown to stimulate invasiveness of cancer cells, promote cancer progression as well as stemness of cancer cells. This paper puts emphasis on the evolving understanding of expression and the non-apoptotic activities of the CD95/CD95L signaling pathway on the function of tumor cells, tumor microenvironment and immune cells. The emerging evidence to support the role of CD95/CD95L signaling in the anti-tumor immune response will be presented in the context of various malignancies and the modalities of potential therapeutic interventions via selective CD95L inhibition in combination with traditional interventions such as RT, chemotherapy and immune checkpoint inhibitors.

Cooperation between ETS transcription factor ETV1 and histone demethylase JMJD1A in colorectal cancer

ETS variant 1 (ETV1) is an oncogenic transcription factor. However, its role in colorectal cancer has remained understudied. The present study demonstrated that ETV1 downregulation led to reduced HCT116 colorectal cancer cell growth and clonogenic activity. Furthermore, the ETV1 mRNA levels were enhanced in colorectal tumors and were associated with disease severity. In addition, ETV1 directly bound to Jumonji C domain-containing (JMJD) 1A, a histone demethylase known to promote colon cancer. ETV1 and JMJD1A, but not a catalytically inactive mutant thereof, cooperated in inducing the matrix metalloproteinase (MMP)1 gene promoter that was similar to the cooperation between ETV1 and another histone demethylase, JMJD2A. RNA-sequencing revealed multiple potential ETV1 target genes in HCT116 cells, including the FOXQ1 and TBX6 transcription factor genes. Moreover, JMJD1A co-regulated FOXQ1 and other ETV1 target genes, but not TBX6, whereas JMJD2A downregulation had no impact on FOXQ1 as well as TBX6 transcription. Accordingly, the FOXQ1 gene promoter was stimulated by ETV1 and JMJD1A in a cooperative manner, and both ETV1 and JMJD1A bound to the FOXQ1 promoter. Notably, the overexpression of FOXQ1 partially reversed the growth inhibitory effects of ETV1 ablation on HCT116 cells, whereas TBX6 impaired HCT116 cell growth and may thereby dampen the oncogenic activity of ETV1. The latter also revealed for the first time, to the best of our knowledge, a potential tumor suppressive function of TBX6. Taken together, the present study uncovered a ETV1/JMJD1A-FOXQ1 axis that may drive colorectal tumorigenesis.

MUC1-induced immunosuppression in colon cancer can be reversed by blocking the PD1/PDL1 signaling pathway

Mucin1 (MUC1) upregulation in colon cancer has been linked to poor patient outcomes and advanced stage at diagnosis. This is partially due to MUC1-mediated inhibition of T-cell proliferation affecting efficient lysis by cytotoxic lymphocytes, which contributes to escape from immune surveillance. In the present study, human colorectal cancer tissues were collected, and MUC1-positive and MUC1-negative colon cancer mouse models were prepared; subsequently, the number and function of immune cells in tumor tissues were measured using flow cytometry. The present study revealed that MUC1, as a tumor-associated antigen, can recruit more tumor-infiltrating lymphocytes into the tumor microenvironment compared with MUC1-negative colon cancer, but that these cells could not serve antitumor roles. Conversely, the present study demonstrated that MUC1-positive colon cancer attracted more regulatory T cells (Treg cells), myeloid-derived suppressor cells (MDSCs) and tumor-associated macrophages (TAMs) to the tumor site than MUC1-negative colon cancer. Furthermore, the data suggested that programmed death protein 1 (PD1)-programmed death ligand 1 (PDL1) expression is greater in MUC1-positive colon cancer. Blocking the PD1-PDL1 signaling pathway reduced the percentage of Treg cells, MDSCs and TAMs in the tumor microenvironment, enhanced T-cell cytotoxicity and inhibited tumor growth, prolonging the survival time of MUC1-positive tumor-bearing mice. Therefore, the present study elucidated the role of MUC1 in tumor immune escape and provides a foundation for the application of PDL1 inhibitors to MUC1-positive colon cancer.

Identification and clinical validation of metastasis-associated biomarkers based on large-scale samples in colon-adenocarcinoma

AIM

Distant metastasis is the main cause of death in patients with colon-adenocarcinoma(COAD). Due to the lack of effective molecular markers and treatment, the prognosis of patients with metastatic colon cancer is still rather poor.

METHODS

Metastatic related signature (MRS) of stage I and stage IV in colon cancer were identified from different cohorts. Univariate cox regression is used to analyze the relationship between MRS and the overall survival. L1000FWD and DGIdb databases are used to identify molecular drugs. Expression and functional experimental validation of the hub MRS were carried out.

RESULTS

16 MRS were identified, of which 14 MRS was significantly correlated with overall survival. Further functional enrichment analysis showed that MRS was significantly involved with important biological functions such as cell migration, and apoptosis. As important metastatic related genes, GSR, FAS and CYP1B1 have significant interaction with drug molecules. Further studies have confirmed that the expression of FAS and GSR is low, and inhibition of its expression can promote the metastasis of COAD. CYP1B1 expression is highly expressed, and inhibition of its expression can attenuate the malignant biological behavior of colon cancer.

CONCLUSION

Our research could increase the understanding of the mechanism of colon cancer metastasis and provide theoretical basis for the treatment of metastatic colon cancer.

TIMP-1-Mediated Chemoresistance via Induction of IL-6 in NSCLC

Elevated tissue inhibitor of metalloproteinase-1 (TIMP-1) is a negative prognosticator in non-small cell lung carcinoma NSCLC patients. This study sought to identify mechanisms whereby TIMP-1 impacts anticancer therapy. Using NSCLC cells and their TIMP-1 knockdown clones, we examined the chemoresistance against two chemotherapeutic agents, Gemcitabine and Cisplatin, as identified by increased apoptosis in the knockdown clones. A bead-based cytokine screening assay identified interleukin-6 (IL-6) as a key factor in chemoresistance. Exogenous human recombinant rhTIMP-1 or rhIL-6 resulted in reduced apoptosis. IL-6 expression was closely correlated with TIMP-1 kinetics and was upregulated by the addition of exogenous TIMP-1 while TIMP-1 neutralizing antibodies delayed IL-6 elevation. IL-6 production was regulated by TIMP-1, exerting its effect via activation of downstream signal transducer and activator of transcription 3 (STAT3) signaling. Both molecules and their documented transcription factors were upregulated and activated in chemoresistant NSCLC cells, confirming the roles of TIMP-1 and IL-6 in chemoresistance. To examine the role of these genes in patients, survival data from lung adenocarcinoma (LUAD) patients was curated from the cancer genome atlas (TCGA) database. Kaplan-Meier analysis found that individuals expressing low TIMP-1 and IL-6 have a higher survival rate and that the two-gene signature was more significant than the single-gene status. We define for the first time, a regulatory relationship between TIMP-1 and IL-6 in NSCLCs, suggesting that the TIMP-1/IL6 axis may be a valuable prognostic biomarker. Therapeutic interventions directed at this dual target may improve overall prognosis while negatively affecting the development of chemoresistance in NSCLC.

Transcriptome Sequencing Investigated the Tumor-Related Factors Changes After T. gondii Infection

Toxoplasma gondii is an intracellular parasite and causes a global epidemic parasitic disease. T. gondii-infection could inhibit the growth of tumor. In this study, the transcriptomes of samples were detected by deep sequencing analysis. The transcriptome data was compared with reference genome to perform sequence alignment and the further analysis. The analyses of differential expression and the differentially expressed genes were performed in the present study. Genes involved in P53 signaling pathway, COLORECTAL cancer pathway, NON-SMALL CELL LUNG cancer signaling pathway, and BREAST cancer signaling pathway were up-regulated or down-regulated among the samples. The KEGG analysis indicated that the cancer pathways changed after infection of T. gondii. Furthermore, tumor-related mRNAs from different samples had a large difference, which suggested that the difference might provide important information in resisting cancer. The protein results indicated that tumor-related protein changes occurred after infection of T. gondii. In conclusion, the infection changed the cancer pathways, which could possibly inhibit the growth of tumor.